1. Field of the Invention
The invention relates to additives for use in preparing composite panels. The invention particularly relates to additives useful for imparting resistance to moisture absorption and swelling to composite panels.
2. Background of the Art
Composite boards, also known in the art as composite panels may be made from wood and have the features of natural wood. When manufacturing composite boards, such as medium density fiber (MDF) boards or particle boards, wood is first ground into wood chips of a desired size. The wood chips are then mixed with a binder in a blender until uniformly blended.
The homogenized mixture is then extruded or molded into a desired shape. The composite board may be coated with polyvinyl chloride (PVC), melamine, metal, foil, impregnated paper, wood veneer that is stained and sealed or polyester to make the composite board decorative and wear resistant and to provide other properties. In some applications, the hardened composite board is then cut to a desired shape and size, and then further processed by cutting, drilling, or edging to create a component part. The composite boards may be used as cabinets, molding, storage units, desks, or other products.
During the last decade oriented strand board (OSB), another form of composite panels, has become a particularly important wood product in the home construction industry. Since its appearance in 1978, OSB has become the most rapidly growing wood-based composite product. OSB is primarily used as a structural panel, which in the past was dominated by softwood plywood.
Still another form of composite panels are the so called “gypsum boards.” Conventional gypsum wallboard or drywall is typically manufactured from a gypsum plaster slurry which is put between two layers of paper. More specifically, in the conventional method, a wet slurry of gypsum is poured on a conveyor between two layers of paper, and the slurry is allowed a certain amount of time to set. In gypsum wallboard, the two layers of paper contain the slurry and provide the tensile strength required in installation and use. Gypsum board composite panels may include cellulose and other materials in addition to gypsum.
It would be desirable in the art of making composite panels to increase the moisture resistance of all such panels.